Telephone-exchange system.



. J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAR.8,1912.

Patented Feb. 16, 1915.

JaGI-I-T, OF WASHINGIQN, DISTRICT 0F COLUMBEA,'ASSIGNOR,, MESNE ETTtEElQTlf5, '10 FREDEERZEC C. STEVENS, 0F ATTIGA, NEW YORK.

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Specification of Letters Patent. Patented Feb, 1485, M915,

Application filed March 8, 1912. Serial No. 682,387.

To 'aZZ whom it may concern:

Be it'known that T, JOSEPH L. WRIGHT, a citizen of the United States, and resident of Washington, District of Columbia, have invented certain new and useful Improvements in Telephone-Exchange Systems, of

which the following is a specification.

My invention relates to telephone exchange systems, particularly to the signaling circuits associated with link or cord-circuits for efiecting connections between telephone lines.

control exercised in this manner prevents the operator from signaling subscribers, unless the calling subscriber has his line circuit closed when the circuit is finally established. After the circuit is established the ringing is under control of the operator and the called subscriber. The operator can dis able the signaling circuit by withdrawing the plugs, and the called subscriber can disable the same by. removing his receiver during a non-signaling interval.

My invention is illustrated in the accompanying drawing, wherein the subscribers station at A is equipped with apparatus usual in common battery systems. The line wires from this station terminate in the jack 5 and also through the line relay E and ground. through the contacts of the cut-01f relay D. The answering plug P and the calling plug P of the cord-circuit are joined together by the conductors indicated in heavy lines for conversational purposes, and,

these conductorsare separated by' the condensers 30 and 40. The relay H and retardation coil I are connected to the tip and sleeve conductors of the answering plug and furnish talking current for the calling subscriber. The relay N and the retardation coil' S are connected to the tip and sleeve conductors of the calling plug and furnish talking current to the called subscriber. The

relay K is placed in series with the cut-ofi relay D when the plug is placed in the jack. The relay D disconnects the relay E and ground from the line, while the relay K closes the circuit of the lamp G through the contacts of relay H. The relay K also maintains the locking circuit of the relay M until the called party answers, or until the plugs are withdrawn from the jacks. The relay L is placedin series with the cutoff relay of the called line when the plug is placed in the jack, and when energized closes the circuit of the supervisory lamp T through the contacts of the relay N. The relay L, together with the relay M jointly control the circuit of relay R. This latter relay when energized, connects generator current to the called line and also places the relay 0 under control of the commutator Y. This commutator acting intermittently, opens and closes the circuit of the relay 0. These commutators U and Y may be common to a group of links. The condenser X is individualto a link circuit and is interposed to prevent" interference between the tip relays of various other link circuits where the commutator U is made common to a group. When the relay 0 is energized, the tip relay N and retardation coil S are disconnected and placed beyond,

controlof the called subscriber. .After the relay R is energized, generator current from W isconnected through the commutator U in series with the condenser X, this relay remaining continuously energized until the control circuit is disabled. The commutators Y and U are arranged so that the relay 0 is energized, before the generator is connected through the commutator U, and also maintains the circuit of the relay 0 until the generator current is disconnected by the commutator U. The called subscriber upon answering, when the relay 0 is deenergized, closes the circuit of the relay N, disconnects relay M, which in turn disconnects relay R. This latter relay then disconnects relay 0 and prevents any further action of the generator current in this particular connection,

Having'described the circuits in a general way, I will .now point out the detailed operation in eflecting a connection from the calling subscriber A to the called subscriber C. Subscriber- A removing his receiver oloses the circuit of the relay E, which in ,ner and upon getting the proper number from the calling subscriber, places the plug P into the jack thereby vplacing relays L and D in series. The operation of relay L closes the circuit of relay R as follows! battery B, contacts of L, 7,'contacts of M, relay R to' ground. The operation of relay R connects commutator Y to the relay 0 as follows: ground, Y, 13, contacts of R, 12, '0,

battery B. The operation of this relay disconnects the relay N and the coil S. Immediatly afterthe operation of relay 0, generator W is connected to the called line as follows: ground, W, U, X, contacts of R, 11, 101, ringer and condenser at C, 102, 8, 21, contacts of R to ground." This generator current causes the bell at C to ring so long as the generator circuit is completed through the commutator U. After this generator current is cut-off by the commuta tor, the, circuit of the relay 0 is opened by the commutator Y", .allowing the relay N and the coil S to become connected to the ti and sleeveconductors. The subscriber at answering at this time closes the-circuit of relay N'. The action of this relay extinguishes the lampT, notifyiiig the operator that the called party has answered. This relay also closes the 1 tip conductor between the' calling and answering plugs and also disconnects relay M. Relay M becoming disconnected releases relay R, which in turn disconnects relay 0 from the commutator Y. The calling and called subscribers are now connected and thesignaling circuit disabled. When the subscribers are through talking, the lamps G and T are lighted and the operator, upon getting this disconnect signal, removes both plugs from the jacks. It will be noted that the relay M can-only be energized-when relays H and K are operated, the relay H closes the starting circuit of the relay M, while the relay K maintains the circuit when it is once established. Controlling the circuits in this mannerprevents the operator from ringing .or calling any subscriber unless a call actually originates and the connection put through in the regular manner. In order to enable the operator to ring at any other time, the wire22 instead of leading to a contact in relay H could be connected directly to wire 15 leading'to a contact in relay K; The circuit arranged inthis manner would give the opera= tor control of the ringing circuit by sim ly placing an answering plug into the jack of a non-busy line which would energize the relay M without anyactio'n of the relay H.

For emergency, the operator could beprovided with a button which would connect ground directly to the wire 22.

vI have shown my invention as applied to a cord-circuit in connection w th a manual.

exchange,-but it could readily be applied to other forms of link circuits without departinglfrom the spirit of the invention.

aving thus described my invention,

what I desire to secure by Letters Patent is:

1. In a telephone exchange system, subscribers lines, a link circuit for. interconnecting them, a ringing relay arranged to be continuously energized to apply ringing current to the calling end of said link through its own contacts,'an auxiliary relay arranged when actuated to sever the link circuit, "a n Y intermittent circuit closer controllingthe' circuit of said auxiliary relay, and means] controlled by the called subscriber for dis-1 abling both the ringing and auxiliary relays when a call is answered.

2. In a telephone exchange system, subscribers 'lines,-a link circuit for interconnecting them, a ringing relay a'rranged'to be continuously energized to apply ringing current to the calling end of, said link through its own contacts, a source of ringing current together with means connecting the same intermittently-to the contacts of said ringing relay, an auxiliary relay arranged -when actuated to sever the link circuit, an

intermittent circuitcloser controlling the circuit of said auxiliary relay in synchr'onism with the application of ringing current to the contacts of the ringing relay, and means controlled by the [called subscriber for disabling both the ringing and auxiliary relays when a call is answered.

calling subscriber at the initiation of a con- ,nection, to primarily control the action of said relay, and means controlled in'the establishment of. the connection to complete the action of said relay andto remove the same from the control of the calling subscriber 4. Ina telephone exchange system, a calling and. called subscribers line, a link circuit for interconnecting them, a ringing relay and generator therefor, together with a control circuit for said relay, a locking relayin said circuit, means under control of the calling subscriber for actuating said locking relay to maintain thecontinuous action of said ringing relay, and means under control of the called subscriber for disabling said relays.

5. In a telephone exchange system, a calling and a called subscribers line, a link circuit for interconnecting them, a ringing generator, together with connecting means and a control-circuit therefor, a relay in said circuit initially controlled by the vcalling subscriber for maintaining the continuous actuation of the connecting means; means at intervals under control of the called sub- JOSEPH L. WRIGHT.

Witnesses ARTHUR L. BRYANT, E. L. GREENEWALD. 

